Assay of phenol sulphotransferase in human blood

An assay of phenol sulphotransferase in human blood with 4-hydroxy-3-methoxyphenylethylene glycol as partial substrate is described. The pH optimum with this substrate is 8.0. To demonstrate the heterogeneity of the enzyme in blood an alternative partial substrate, 4-methylumbelliferone, at an optimal pH of 7.4, is used. Enzyme activity is linear with time up to at least 60 minutes of incubation. With 4-hydroxy-3-methoxyphenylethylene glycol as the substrate a linear relation between phenol sulphotransferase activity and enzyme concentration exists. Phenol sulphotransferase activity shows no correlation with age or sex of healthy subjects. Varying ratios of the enzyme activities toward both substrates support the idea of two phenol sulphotransferases in blood. As nevertheless a significant correlation exists between both sulphotransferase activities we conclude that neither substrate is sulphated exclusively by one of the two enzymes. Because preparative procedures for platelets may lead to considerable losses of specific subpopulations with relatively low or high enzyme activity, one of the advantages of using whole blood is that the activity in the whole platelet population is determined.